They may be able to tell that you have read it, but they shouldn't be able to get your IP address. Since 2013 Gmail has proxied images through their own servers, so "tracking pixels" will only get the IP of the Gmail server.

Note that if you click on any links in the email, they may get your IP address.

They may be able to tell that you have read it, but they shouldn't be able to get your IP address. Since 2013 Gmail has proxied images through their own servers, so "tracking pixels" will only get the IP of the Gmail server. This only applies to the web client though (and I believe Gmail's official smartphone apps do this as well, but I haven't tested). If you're using a 3rd party IMAP client then it may reveal your IP address when loading images.

Note that if you click on any links in the email, they can get your IP address no matter what client you use, unless you check the link destination first and verify it's to a domain that you trust and not a tracking domain.